In the operation of various large, over-the-road type vehicles (e.g., semi-trailer trucks), it is oftentimes desirable from a safety standpoint as well as from the standpoint of reducing the initial and maintenance costs of the vehicle braking system that the vehicle engine have the capability of operating in a gas compression braking mode.
Heretofore, in order for the engine to have such a capability required the inclusion of costly and complex controls which were difficult to install, maintain and service. Furthermore, in certain prior slave/master hydraulic braking systems, undesirable delays are encountered in the initiation of the exhaust valve openings during the braking mode operation of the engine. Another disadvantage of these prior slave/master hydraulic braking systems is that significant mechanical loads are imposed on the exhaust valve components when the slave piston is forced by fluid actuating pressure at accelerating speed across the lash distance and impacts the cross-head of the exhaust valve. In many prior reset mechanisms there is no way to vary the timing of the valve opening event because it is determined by the amount of lash that is set when the brake is installed.